THE latest ratings for BBC 1, published yesterday, show the extent of the crisis that in the last few days has forced the corporation to drop its head of Light Entertainment, Jim Moir, and to cancel Esther Rantzen's long-running That's Life.

Figures from BARB (the Broadcasters' Audience Research Board) show that the main BBC channel won only 28.9 per cent of the total television audience for the week ending 27 June, its lowest weekly share since 1985.

One reason is that it was the first week of the Wimbledon fortnight, which always increases audiences for BBC 2. Yet even in the week before Wimbledon, BBC 1 attracted only 30.7 per cent of viewers. ITV's rival Channel 3 scored 41.4 per cent that week and 39 per cent in the first Wimbledon week, which saw BBC 2's share increase from 9.5 per cent to 15.1 per cent.

Although the BBC discourages making a link between poor ratings and Mr Moir's transfer to a non-programme role, it is known that Alan Yentob, who has been running BBC 1 since the beginning of the year, believes that the schedule he inherited has a fusty, old-fashioned look. This is especially so in Light Entertainment, which has scored only one palpable ratings hit in recent months - Noel Edmonds's Noel's House Party.

Will Wyatt, managing director of BBC Television, said yesterday: 'Our comedy is the best I can remember.' But many of the BBC's critical successes - Absolutely Fabulous, Alas Smith and Jones, Have I Got News for You? - play to audiences of up to 5 million on BBC 2, although the latter reached 7.5 million, counting the repeat.

ITV, by contrast, manages to get significant audiences for its best light entertainment shows. Yesterday's figures for the week ended 27 June put four such shows in the overall top 20 - Wheel of Fortune (10.3 million), Through the Keyhole (9.84 million), Surprise Surprise (9.77 million) and Stars in Their Eyes (9.02 million). When the BBC tries its hand at so-called 'people' formats - Old Flames, Caught in the Act and Bobby Davro: Public Enemy No. 1 - it usually fails.

Mr Wyatt said: 'We do want to have popular entertainment shows in the early evening. But BBC 1 will not be a success if it gains 5 or 6 per cent in the share but does it with a lot of high prize game shows.'

Critics inside and outside the BBC believe that the failure in light entertainment is a direct result of the new 'Birtian' philosophy, which downgrades entertainment at the expense of news and current affairs.

If the BBC wants to regain a mass audience for comedy and entertainment it will need to appoint someone who knows the business. This is why Alan Boyd, now with Grundy, which produces Neighbours, is the most interesting of those being mentioned to succeed Mr Moir. He was head of light entertainment at London Weekend and would be a good populist foil to Mr Yentob, whose background is in music and the arts.

Mr Yentob cannot be blamed for the collapse of BBC 1's ratings because he is still showing programmes he inherited. The only other time BBC 1's share fell below 29 per cent was in 1985, when Michael Grade had been Controller for about as long as Mr Yentob has now. A year later Mr Grade's channel was neck and neck with ITV.